1. Field of the Invention
This invention relates generally to butterfly valves and, more particularly, to a butterfly valve and associated controls for use as an inlet valve for a fire truck pump used in firefighting applications.
2. Description of the Prior Art
At a fire scene, it is desirable to place the fire truck with its equipment as close to the fire as practical and to begin the firefighting operation as soon as possible by delivering water onto the fire from the fire truck""s on-board water tank. At the same time, a large diameter hose is run to the nearest available hydrant or pressurized water supply and one end thereof is connected thereto, the other end of this hose being connected to the inlet connection for the pump on the fire truck. This procedure requires the provision of a valve on the inlet of the fire truck pump constructed and arranged for use in a firefighting operation whereby the fire pump can be placed in operation with water supplied from the truck""s on-board water tank while the large diameter hose is being run to and connected to the nearest hydrant or pressurized water supply. Once the hydrant is opened and the large diameter hose is charged with water, the inlet valve is opened and the tank valve is closed so that the fire pump is supplied with water from the hydrant.
The term xe2x80x9clarge diameter hosexe2x80x9d is used in the art to designate a fire hose having a diameter of at least 3.5 inches, and, more typically, about 5 to 6 inches.
The presently available valves of the above type being used as fire truck pump inlet valves are mainly xe2x80x9cafter marketxe2x80x9d units that are installed by the fire department. These valves are long and extend outside the body work of the truck and can interfere with the normal operation of the fire pump. Also, the general overall design of these valves is such that they are unacceptable by fire truck manufacturers to be considered as a built-in component. These valves are available with only one form of actuation, usually manual, and cannot be adapted easily to another form of actuation. Another problem with these valves that makes them unacceptable as built-in units is the fact that they do not meet NFPA (National Fire Protection Association) criteria for pump performance during draft operations.
There are essentially four of the above-discussed type of inlet valves for fire truck pumps that make up the majority of the present-day market. These valves are the ANGUS HI-VOL GATE VALVE, the HARRINGTON/AWG PISTON INTAKE RELIEF VALVE, SNAP-TITE PISTON INTAKE VALVE, and the HARRINGTON/AWG BALL INTAKE RELIEF VALVE. None of these valves is of the butterfly-type valve construction.
Hale Fire Pump Company manufactures a butterfly valve for use as an inlet valve for a fire truck pump, this valve being known as the xe2x80x9cHale type 60WP Series butterfly valvexe2x80x9d. However, this valve is not designed for use with large diameter hoses. This valve, which is mounted behind the operator panel, has a butterfly type valve member and is actuated by means of an air cylinder which is operable to move the valve between only two flow control positions, i.e., a fully opened and a fully closed position.
It is the general object of the invention to provide an improved butterfly valve and associated controls for use in controlling the flow of water through a large diameter fire hose to the inlet of a fire truck pump, such as a midship pump.
One improved feature of the valve in accordance with the invention is that it is constructed and arranged to provide for a safer operation. The butterfly valve in accordance with the invention is installed between the suction tube and the suction tube extension on a midship mounted pump of a fire truck in a location such that the valve is positioned behind the pump operator panel. With the prior art valves, the inlet valve for the large diameter hose is positioned to extend beyond the pump operator panel at a location where the operator usually stands during a firefighting operation whereby the operator is susceptible to injury in the event that the valve should be blown apart by the action of the high pressure water supplied thereto. With a large diameter hose, typically five or six inches in diameter, the slug of water that comes down the hose at a rate of 1,500 gallons per minute, or the like, can cause the structural failure of the inlet valve. There have been actual cases of serious injury to firefighters by this circumstance. By locating the butterfly valve in accordance with the invention behind the operator panel, if a structural failure of the valve should occur, the operator is provided with some degree of protection by the panel which is interposed between the failed valve and the operator. In this regard, a pressure relief valve is mounted on the valve body and behind the operator panel.
Another safety feature provided by the valve in accordance with the invention is that it is designed to be suitable for remote control. To this end, the operation of a valve member, as well as the operation of an air bleeder, can be controlled from a safe remote location. If the valve should fail structurally because of the water pressure exceeding the capability of the valve, the compressed air in the system will expand creating an additional threat to injury of the operator. However, by positioning all of the controls so that the operator will be standing at a remote or protected location, the operator is in a much safer position.
Another feature of the invention is to provide a butterfly valve design whereby the disk and the body of the valve are constructed to exceed the 500 PSIG hydrostatic pressure requirement of the National Fire Protection Association. By reason of this design, the valve disk and valve chamber are constructed to be larger than the prior valves, which are rated to have only a sealing ability at about 250 PSIG.
Another feature of the butterfly valve design in accordance with the invention is that it is designed to provide a minimum obstruction to flow to thereby achieve the least pressure drop as the water enters the pump. The National Fire Protection Association requires a flow rate of up to 1,500 gallons per minute in order to get all the fluid through a single suction connection from a 10 foot lift through 20 feet of hose. None of the prior art valves can achieve this whereas this is achieved by the butterfly valve design in accordance with the invention, which valve is considered full flow up to 1,500 gallons per minute.
Another feature of the invention is to provide an improved air bleed means. There is disclosed a manual air bleed construction as well as a novel automatic air bleed design.
Another feature of the invention is the provision of the valve of the indicated type which has two modes of actuation, namely, a manual actuation means as well as a power operated actuation means. More specifically, the power operated means utilizes an electric motor which actuates the butterfly valve disk to a desired flow control position. The manual actuation means is operable as a manual override to permit operation under emergency or abnormal operating conditions whereby the electric motor is not usable.
Another feature of the valve in accordance with the invention is the provision of electrical means for indicating the position of the valve disk. This means is operable to indicate whether the valve is closed, open, or at some in-between location, such as when it is traversing between the closed and open positions.
Another feature of the invention is the provision of a clutchable handwheel means for use with the manual actuating means for the valve.
Another feature of the invention is that the motor actuation of the valve disk is designed to operate through a predetermined time delay period as it moves the valve between closed and open positions. This serves as another safety feature for the inlet valve by causing the valve disk to open or close gradually.